and IPv6

Fri Nov 18 20:05:43 UTC 2016

I tested from my home and happy eyeballs is not falling back to IPv4.

So, I tend to suspect that is not ICMPv6 filtering, but something else, such as wrong load balancer or ECMP configuration.


-----Mensaje original-----
De: NANOG <nanog-bounces at> en nombre de Carl Byington <carl at>
Responder a: <carl at>
Fecha: sábado, 19 de noviembre de 2016, 3:22
Para: <nanog at>
Asunto: Re: and IPv6

    > > I am working with at, trying to explain the
    > problem.
    The intersection of government bureaucracy and technical issues is
    frustrating to say the least. I just sent the message below, but have no
    expectation that it will change anything. 
    On Fri, 2016-11-18 at 12:39 +0000, CLEV Pay Gov wrote:
    > It would be best to discuss this via phone.  Please contact our help
    > desk at the number below and we could see if there's anything we could
    > do over the phone to help troubleshoot.
    That is hopeless. Verbal technical discussions rarely work unless both
    sides can see the same text. Have you ever tried (while talking on the
    phone) to get someone to type in without making a bunch of
    mistakes in the spelling??
    Anyway, just for my amusement, I did call 800-624-1373, Option #2, and
    am on the line now, trying to explain this. 10 minutes and counting. Ok,
    there does not seem to be any overall ticket for " does not work
    at all". They refuse to open a tech support ticket.
    > If not, we may need to open a ticket for our technical support.
    Please open a ticket, and attach the following text for your tech
    support folks. Alternatively, have them look at the " and ipv6"
    thread on nanog:
     has an IPv6 address of 2605:3100:fffd:100::15, but that
    machine or its upstream routers are filtering icmpv6 messages. That web
    site is not accessible from systems with an MTU of 1280 bytes.
    The test case is:
    echo -e 'GET /public/home HTTP/1.0\n' | \
    openssl s_client -servername -ign_eof -connect \
    Run that (or just use a browser to try from a
    system with a 1500 byte MTU, and it works. Run it from a system with
    upstream connectivity via a tunnel, so the path MTU is smaller, and it
    fails. Such tunnels are common for IPv6.
    Please stop filtering icmpv6.

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